// Problem 11 - http://projecteuler.net/
//
// What is the greatest product of four numbers on the same straight line in the 20 by 20 grid?

package projecteuler

import (
	"fmt"
	"strings"
	"strconv"
)

func maximum(a, b int)int{
	if a>b{return a}
	return b
}

func Euler11() string{
	str :=	"08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08\n" +
				"49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00\n" +
				"81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65\n" +
				"52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91\n" +
				"22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80\n" +
				"24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50\n" +
				"32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70\n" +
				"67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21\n" +
				"24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72\n" +
				"21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95\n" +
				"78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92\n" +
				"16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57\n" +
				"86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58\n" +
				"19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40\n" +
				"04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66\n" +
				"88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69\n" +
				"04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36\n" +
				"20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16\n" +
				"20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54\n" +
				"01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48\n"
	max := 0
	prod := 1
	lines:=strings.Split(str,"\n", 0)
	numbers := make([]int,400)
	//Copy everything in sparse list of integers
	for i:=0;i<20;i++{
		line:=strings.Split(lines[i]," ",0)
		for j:=0;j<20;j++{
			numbers[i*20+j], _= strconv.Atoi(line[j])
		}
	}
	//Parsing every possible start for lines,cols,1 diag
	for i:=0;i<16;i++{
		for j:=0;j<16;j++{

			//lines
			prod = 1
			for k:=0;k<4;k++{
				prod *= numbers[i*20+j+k]
			}
			max = maximum(max,prod)

			//columns
			prod = 1
			for k:=0;k<4;k++{
                prod *= numbers[(i+k)*20+j]
            }
			max = maximum(max,prod)

			//diagonals top,left-bottom-right
			prod = 1
			for k:=0;k<4;k++{
                prod *= numbers[(i+k)*20+j+k]
            }
			max = maximum(max,prod)
		}
	}
	//Parsing for the other diag
	//The solution is actually there
	for i:=3;i<20;i++{
		for j:=0;j<16;j++{
			prod = 1
			for k:=0;k<4;k++{
				prod *= numbers[(i-k)*20+j+k]
			}
			max = maximum(max,prod)
		}
	}


	return fmt.Sprint(max)
}
